Conventional machine arrangements for bottle and can manufacturing are typically linear and are generally referred to as machine lines. That is, the machine lines, with each and every processing and/or forming machine, extend in a single line. The articles are passed through the machine line only once to achieve a desired stage of manufacture. Such a “single-pass” arrangement may take up a large amount of space in a warehouse, factory, or other location. Occasionally, buildings are not large enough or long enough to house such complex and long machine arrangements. For example, in bottle or can operations, many different types of processes need to be performed on the bottle or can, such as necking, curling, expansion, trimming, etc. Each type of process may also require a plurality of machines in order to sufficiently perform the necessary process. For instance, necking operations may require multiple operations with multiple machines in order to properly neck a bottle or can that is of a certain length or size. A downside of the conventional single-pass arrangement is that the machine lines may need to include duplicate or additional machines in order to perform the desired function(s), increasing both the cost and footprint of these machines.
Machine arrangements have been developed that perform a single recirculation of cans or bottles. Such an arrangement takes cans or bottles from a downstream point after the cans or bottles have passed through the machine line once and transports the cans or bottles upstream for a second pass through the machine line. That is, each processing or forming machine in the machine line receives cans or bottles at two different stages of manufacturing. On the first pass through the machine line, each machine performs a first operation on the cans or bottles. These operations result in cans or bottles at a single stage of manufacture. These cans or bottles are then recirculated for a second pass through the machine line. On the second pass, each machine performs a second operation on the can or bottle, resulting in a can or bottle at the desired stage of manufacture. The can or bottle is then output from the machine line and passed downstream for packaging or further processing. These machine arrangements achieve the same number of required process stages with as little as half the number of line starwheels versus a single-pass counterpart. This results in a generally lower-cost machine with a generally smaller footprint, but sacrifices throughput of the machine. In such a two-pass system, the cans or bottles received by the recirculator are always at the same stage of manufacture. Such systems are non-synchronous. The non-synchronous nature of such a system can prevent performance of more than one recirculation because the cans or bottles may be placed in the wrong position for recirculation. Such improper placement can result in collisions, jams, and/or non-uniform products being delivered downstream from the system.
Thus, a need exists for systems and methods for performing multiple recirculations of containers to achieve a desired stage of manufacture while lowering system costs and/or space occupied by the system.